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991.
Anastasia Terzopoulou Marcus Hoop Xiang‐Zhong Chen Ann M. Hirt Michalis Charilaou Yang Shen Fajer Mushtaq Angel Prez delPino Constantin Logofatu Laura Simonelli Andrew J. de Mello Christian J. Doonan Jordi Sort Bradley J. Nelson Salvador Pan Josep Puigmartí‐Luis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13684-13689
Metal–organic frameworks (MOFs) capable of mobility and manipulation are attractive materials for potential applications in targeted drug delivery, catalysis, and small‐scale machines. One way of rendering MOFs navigable is incorporating magnetically responsive nanostructures, which usually involve at least two preparation steps: the growth of the magnetic nanomaterial and its incorporation during the synthesis of the MOF crystals. Now, by using optimal combinations of salts and ligands, zeolitic imidazolate framework composite structures with ferrimagnetic behavior can be readily obtained via a one‐step synthetic procedure, that is, without the incorporation of extrinsic magnetic components. The ferrimagnetism of the composite originates from binary oxides of iron and transition metals such as cobalt. This approach exhibits similarities to the natural mineralization of iron oxide species, as is observed in ores and in biomineralization. 相似文献
992.
Feng Jiang Douglas I. Trupp Norah Algethami Haining Zheng Wenxiang He Afaf Alqorashi Chenxu Zhu Chun Tang Ruihao Li Junyang Liu Hatef Sadeghi Jia Shi Ross Davidson Marcus Korb Alexandre N. Sobolev Masnun Naher Sara Sangtarash Paul J. Low Wenjing Hong Colin J. Lambert 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19163-19169
Together with the more intuitive and commonly recognized conductance mechanisms of charge‐hopping and tunneling, quantum‐interference (QI) phenomena have been identified as important factors affecting charge transport through molecules. Consequently, establishing simple and flexible molecular‐design strategies to understand, control, and exploit QI in molecular junctions poses an exciting challenge. Here we demonstrate that destructive quantum interference (DQI) in meta‐substituted phenylene ethylene‐type oligomers (m‐OPE) can be tuned by changing the position and conformation of methoxy (OMe) substituents at the central phenylene ring. These substituents play the role of molecular‐scale taps, which can be switched on or off to control the current flow through a molecule. Our experimental results conclusively verify recently postulated magic‐ratio and orbital‐product rules, and highlight a novel chemical design strategy for tuning and gating DQI features to create single‐molecule devices with desirable electronic functions. 相似文献
993.
994.
Yao Liu Madhu Sheri Marcus D. Cole Duk Man Yu Todd Emrick Thomas P. Russell 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5733-5737
A new and highly efficient cathode interlayer material for organic photovoltaics (OPVs) was produced by integrating C60 fullerene monomers into ionene polymers. The power of these novel “C60‐ionenes” for interface modification enables the use of numerous high work‐function metals (e.g., silver, copper, and gold) as the cathode in efficient OPV devices. C60‐ionene boosted power conversion efficiencies (PCEs) of solar cells, fabricated with silver cathodes, from 2.79 % to 10.51 % for devices with a fullerene acceptor in the active layer, and from 3.89 % to 11.04 % for devices with a non‐fullerene acceptor in the active layer, demonstrating the versatility of this interfacial layer. The introduction of fullerene moieties dramatically improved the conductivity of ionene polymers, affording devices with high efficiency by reducing charge accumulation at the cathode/active layer interface. The power of C60‐ionene to improve electron injection and extraction between metal electrodes and organic semiconductors highlights its promise to overcome energy barriers at the hard‐soft materials interface to the benefit of organic electronics. 相似文献
995.
Three-dimensional magnetic resonance velocimetry measurements of turbulence quantities in complex flow 总被引:1,自引:0,他引:1
Christopher J. Elkins Marcus T. Alley Lars Saetran John K. Eaton 《Experiments in fluids》2009,46(2):285-296
A magnetic resonance velocimetry (MRV) experimental technique based on magnetic resonance imaging and capable of measuring
the turbulent Reynolds stresses in a 3D flow domain is described. Results are presented in backward facing step flow in a
square channel with a Reynolds number of 48,000 based on step height and freestream velocity at the step. MRV results are
compared to particle image velocimetry (PIV) measurements in the centerplane containing the streamwise and cross-stream axes.
MRV and PIV mean velocity measurements show excellent agreement. MRV measurements for Reynolds normal stresses compare to
within ±20% of the PIV results while results for the turbulent shear are less accurate. 相似文献
996.
In order to predict deformations and internal stresses of articular cartilage replacement material, two viscoelastic diffusion models are proposed in the present study. Also, the remodeling effect of the material seeded with human cells is verified experimentally. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
997.
998.
The present study is concerned with an experimental and numerical investigation of the behavior of sub–clad and surface cracks in cladded components considering the residual stress field due to the welding and heat treatment processes. For this purpose, two large–scale tests on cladded cracked specimens have been performed and analyzed numerically. It is observed that the fracture process is initiated in the heat affected zone of the base metal underneath the cladding whereas the cladding remains intact even in case of a brittle crack extension and arrest in the base material. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
999.
Petta JR Taylor JM Johnson AC Yacoby A Lukin MD Marcus CM Hanson MP Gossard AC 《Physical review letters》2008,100(6):067601
We polarize nuclear spins in a GaAs double quantum dot by controlling two-electron spin states near the anticrossing of the singlet (S) and m(S)= +1 triplet (T+) using pulsed gates. An initialized S state is cyclically brought into resonance with the T+ state, where hyperfine fields drive rapid rotations between S and T+, "flipping" an electron spin and "flopping" a nuclear spin. The resulting Overhauser field approaches 80 mT, in agreement with a simple rate-equation model. A self-limiting pulse sequence is developed that allows the steady-state nuclear polarization to be set using a gate voltage. 相似文献